To produce yarns with high elasticity and so-called "mixed-effect" yarns with different color and texture effects, composite yarns can be formed from one or more basic strands consisting of natural or synthetic filaments and having a limited elongation under tension so that they can be termed inelastic yarns or strands. Included among such strands are textured nylon filaments and strands which are monofilamentary in nature but textured, as well as multifilament or discontinuous-filament yarns or strands.
The elastic strands may be composed of elastomeric materials, such as rubber.
The joining of the two types of strands to form the composite yarn may be done in such a way that the composite yarn will have a pleasant feel or "hand" and to bring out the aesthetic characteristics of the composite yarn, while nevertheless retaining the elastic qualities thereof. This means that the elastic strands which provide the high degree of elongation and rebound from deformation should be provided in the interior of the composite yarn while the inelastic strands dominate the external surface of the composite yarn.
In the past, this has generally been accomplished by twisting the inelastic strand or strands in a helical pattern around the elastic strand or strands so that the latter form a core encased in the twisted sheath formed by the inelastic strand or strands.
Since the twisting process is comparatively slow, its productivity is poor and the cost of the composite yarn as a result is high. This applies when composite elasticized yarns are formed from inelastic strands of synthetic fiber such as nylon, polyester, polypropylene and the like which may be subjected to texturizing and false twisting.
It is possible to produce a composite yarn by matting and coalescing fibers of an inelastic strand to an elastic strand by subjecting these fibers to deflection by a pneumatic jet. Up to now, however, there has not been available to my knowledge an effective machine for carrying out a process of this type or, for that matter, an effective process for the high production rate generation of composite yarns.
It appears, that attempts to mat the aforementioned inelastic strands to the elastic strand have been strongly dependent not only on the types of yarns or strands used, but upon the conditions under which the strands were supplied to the jet, making the product nonuniform in character.